Polycarbonate resins are resins having excellent heat resistance, mechanical properties, optical properties, and electrical characteristics and are widely utilized, for example, in automotive materials, electrical and electronic device materials, housing materials, and materials for use in the manufacture of components in other industrial fields. In particular, flame-resistant polycarbonate resin compositions are suitably used as members for OA and information appliances, such as computers, notebook computers, cellular phones, printers, and copying machines, and sheet and film members.
In these various applications, it is known to blend organosiloxane (silicone) compounds having low surface energy with resins to modify surface properties, such as water repellency, oil repellency, anti-fogging properties, anti-fouling properties, stain removability, moisture resistance, lubricity, abrasion resistance, mold releasability, chemical resistance, and scratch resistance, for the purpose of improving product value. Among others, dimethyl silicone oils can effectively impart water repellency, oil repellency, and other characteristics.
Furthermore, resin lubricants containing polysilane compounds have been proposed (Patent Document 19).
As means for imparting flame resistance to polycarbonate resins, methods for blending a halogen flame retardant or a phosphorus flame retardant with polycarbonate resins have been employed. However, polycarbonate resin compositions containing a halogen flame retardant containing chlorine or bromine sometimes result in low thermal stability or deteriorated hue or cause the corrosion of screws or forming dies of forming machines in shape processing. Polycarbonate resin compositions containing a phosphorus flame retardant sometimes cause degradation of high transparency that is characteristic of polycarbonate resins or result in low impact resistance or low heat resistance, thus having limited applications. In addition, such a halogen flame retardant and phosphorus flame retardant may cause environmental pollution during the disposal and collection of products. Thus, in recent years, it has been strongly desired to impart flame resistance to polycarbonate resins without using such a flame retardant.
Under such circumstances, many metal salt compounds, typically organic alkali metal salt compounds and organic alkaline-earth metal salt compounds, have been recently studied as useful flame retardants (e.g., refer to Patent Documents 1 to 4). Examples of methods for imparting flame resistance to aromatic polycarbonate resin compositions by using an aromatic sulfonic acid alkali metal salt compound include a method that uses a perfluoroalkylsulfonic acid alkali metal salt having 4 to 8 carbon atoms (refer to Patent Document 1) and a method for blending a non-halogen aromatic sulfonic acid sodium salt (refer to Patent Document 2). Such metal salt compounds can be used as flame retardants to impart flame resistance to polycarbonate resins to some extent without adversely affecting their intrinsic characteristics such as mechanical properties, including impact resistance, heat resistance, optical properties, and electrical characteristics.
However, the flame resistance levels achieved by the above-described methods for blending such a metal salt compound with a polycarbonate resin are by no means satisfactory. This is probably because the flame-retardant effect achieved by blending the metal salt compound with a polycarbonate resin results from a catalytic action. Even if the amount of metal salt compound blended is increased to further improve the flame resistance, the flame resistance is not improved and, on the contrary, tends to be lowered. Furthermore, such an increase in the amount of metal salt compound causes a significant deterioration in mechanical properties, such as impact resistance, optical properties, such as transparency, and other physical properties, such as heat resistance and wet heat stability.
An attempt has been made to improve flame resistance by blending an organosiloxane (silicone) compound with a polycarbonate resin (e.g., refer to Patent Document 5).
In particular, methods for blending an organosiloxane compound having a branched structure in the main chain and having an aromatic group have been actively studied (e.g., refer to Patent Documents 6 to 8).
Furthermore, methods for simultaneously blending an organic sulfonic acid metal salt and the above-described organosiloxane compound having a branched structure in the main chain and having an aromatic group have been proposed (e.g., refer to Patent Documents 9 and 10).
However, the methods for blending only an organosiloxane compound according to Patent Documents 5 to 8 practically have very small effects of improving flame resistance and cannot achieve practical levels of flame resistance.
Furthermore, organosiloxane compounds have poor compatibility with and dispersibility in polycarbonate resins, resulting in poor mechanical properties, such as impact resistance, and thermophysical properties. In addition, even the addition of a small amount of organosiloxane compound markedly lowers the transparency of polycarbonate resins, which presents a critical drawback. Moreover, there are other problems such as the generation of a large amount of gas during kneading and shaping of resin compositions, a tendency to cause mold fouling, poor appearances of resin formed products, and sticky surfaces.
In accordance with the methods for simultaneously blending an organic sulfonic acid metal salt and the organosiloxane compound, the methods being proposed in Patent Documents 9 and 10, the amount of organosiloxane compound to be blended can be relatively reduced to improve flame resistance and thus the generation of gas, mold fouling, and poor appearances and stickiness of resin formed products can be suppressed to some extent. However, this cannot prevent deterioration in mechanical properties or thermophysical properties, particularly transparency.
Examples of methods for improving transparency that have been proposed include a method in which an organosiloxane compound having a particular functional group is used to improve compatibility with polycarbonate resins (e.g., refer to Patent Documents 11 to 13), a method using an organosiloxane compound having a phenyl group and a low degree of polymerization (e.g., refer to Patent Document 14), and a method using a low-molecular-weight organosiloxane compound (e.g., refer to Patent Documents 15 and 16).
In accordance with recent studies, polysilanes having the main chain composed of silicon atoms are blended with resins to improve mechanical properties, lubricity, and flame resistance. (e.g., refer to Patent Documents 17 to 19)
Hitherto, fluoropolymers have been blended with thermoplastic resins to improve the melt properties and surface properties, such as sliding characteristics, scratch resistance, water repellency, oil repellency, stain resistance, and fingerprint resistance, of the thermoplastic resins.
Among others, fluoroolefin polymers capable of forming fibrils can effectively modify the melt properties of thermoplastic resins. In particular, the blend of fluoroolefin polymers with flame-retarded thermoplastic resin compositions can improve anti-dripping properties during combustion and thereby can prevent the spread of fire when a thermoplastic resin formed product burns, thus showing excellent blending effects.
In the case where flame resistance is imparted to thermoplastic resins, fluoropolymers generally need to be used in combination with flame retardants because, normally, the addition of a fluoropolymer alone improves anti-dripping properties, but does not improve extinction properties (e.g., refer to Patent Documents 20 and 21).
In recent years, attempts have been actively made to weld thermoplastic resin formed products using a near-infrared laser (so-called laser welding) in automobile, electrical and electronics, and precision apparatus fields. Laser welding methods are noncontact methods, produce no abrasion powder or burrs, and cause minimal damage to products. Thus, laser welding methods have considerable industrial advantages.
Near-infrared light having a wavelength of 800 to 1200 nm is generally suitably used as a laser for use in laser welding for safety and cost reasons. Thus, thermoplastic resin compositions that are highly transparent to light in the near-infrared region are used in a laser welding field (e.g., refer to Patent Documents 22 and 23).
Many thermoplastic resin compositions are used in members for sensing devices, exemplified by various automobile sensing devices, such as face direction detection systems and rain sensors, various security systems, such as face recognition systems, fingerprint recognition systems, and vein recognition systems, and various information/communication devices, such as remote controllers and infrared communication devices. The wavelength of infrared light used in such fields depends on the devices and systems. In general, near-infrared light in the range of 800 to 1500 nm is used. Thus, also in such fields, there is a demand for thermoplastic resin compositions that are highly transparent to light in a near-infrared region.